1. Technical Field of the Invention
This invention generally relates to a system and methods for digital image verification and, more particularly, to an image capturing system and methods for automatically recording and watermarking a plurality of camera and image parameters with a digital image (still and video) for verifying the authenticity of the digital images.
2. Description of the Related Art
It is often necessary to determine the conditions and circumstances (such as time, date, and location) in connection with the capturing of an image. For instance, such information can be of immense value to insurance agencies (e.g., real-estate, auto, and fire), hospitals, news agencies and crime investigating agencies, for confirming the details surrounding an accident so as to assist in the investigation of the accident and preparing the necessary accident reports. Moreover, this information would also be useful for image search algorithms that are based on such information. Therefore, an image capturing device which can automatically record a plurality of parameters with each captured image, such as names of geographic locations, altitude, longitude, time, date, photographer identification, as well as image data such as light intensity, shutter speed and flash status, would be very useful to such agencies.
Furthermore, an image capturing system which could automatically watermark (i.e., hide) the plurality of recorded parameters into each image would be useful for verifying the authenticity of digital pictures, as well as verifying and confirming the circumstances and conditions surrounding the capturing of the digital image. In general, the ability to prove the authenticity of digital images is a burdensome task because there are various commercially available software applications which allow users to manipulate and modify digital images. Therefore, by invisibly watermarking parameters associated with a digital image within the image, the authenticity of the digital image may subsequently be verified by extracting the watermarked parameters and then comparing the extracted parameters with the initially recorded parameters to determine whether they are similar.
There are commercially available film cameras which are capable of recording the time and date on each photographic image. These conventional film cameras, however, do not record additional camera parameters such as location (e.g., altitude and longitude) in an electronically accessible form. Moreover, these traditional film cameras allow a user to set any desired date and time to be recorded with each image, which limits the use of such recorded information for purposes of authenticating digital images.
There are digital cameras that are commercially available which can capture and record the time and date with each image. But like the conventional film cameras, the user can set any desired time and date to be recorded with each image. Moreover, the time and date information are often stored in the header line for the image file. Some digital cameras store these camera parameters in a separate file. The separate file may be encrypted and transmitted along with the image file. The disadvantage with this approach, however, is that the user may create his own camera parameters for an image and then encrypt it and present it as the secure data for the image. Thus, separating the captured image from the encrypted parameter file does not afford a solution to potential tampering of such recorded information.
In addition, there are commercially available cameras which allow other parameters (in addition to time and date) to be recorded with each image. These cameras, however, do not provide means for detecting if such parameters have been modified or if the images have, otherwise, been tampered with. For instance, U.S. Pat. No. 4,574,319 to M. Konishi entitled, “Electronic Camera Having Non-Image Data Recorder,” teaches the association of a magnetic recording area with each image for conventional film cameras. Camera parameters such as shutter speed, aperture value, frame number, location of image, and the name of the photographer for a given image can be stored in the associated magnetic recording area. This invention, however, assumes a trusted environment and does not teach a method for proving the authenticity of such recorded camera parameters.
Next, U.S. Pat. No. 5,506,644 to Suzuki et al. entitled, “Camera”, teaches the connection of a Global Positioning System (GPS) receiver to the camera so as to record the location at which the image was taken. Again, this invention does not deal with proving the authenticity of recorded location parameters and assumes a trusted environment.
Furthermore, U.S. Pat. No. 5,247,356 to J. Ciampa entitled, “Method and Apparatus for Mapping and Measuring Land”, teaches the association of geographical location information with each picture and stores the information in unused portions of an analog image, such as the vertical blanking interval, or in the border of a digital image. The disadvantage to this is that, by storing data in such obvious places, a hacker can easily detect and modify such parameters.
On the other hand, U.S. Pat. No. 5,499,294 to G. Friedman, entitled, “Digital Camera with Apparatus for Authentication of Images Produced From an Image File” teaches a method for verifying the authenticity of a digital image. This invention utilizes the concept of public and private keys. Each camera is assigned a private key. Initially, a hash code based on the contents of the image is computed. The hash code is then used to generate a digital signature using the private key. The digital signature is then decrypted using a public key to obtain the hash code which is then compared with the original hash code of the image to determine if any alteration has occurred. In addition, the invention teaches that additional camera parameters such as location, orientation, shutter speed, f-stop, etc., may be recorded in the border of the image and be used to compute the hash function. One disadvantage with this approach is that the image file and the digital signature are separate entities. Therefore, two entities are needed every time an image has to be authenticated. Further the two entities may become disassociated during transmission, thus, making it difficult to track them down.
Based on the above prior art, there are no commercially available image capturing devices which afford automatic recording and watermarking of a plurality of camera and image parameters with each captured digital image. By watermarking (i.e. hiding) the recorded parameters throughout each captured image in a non-obvious manner (in addition to, or in lieu of, storing the parameters in an image header or in a separate file), it is difficult to detect and tamper with the embedded data. Accordingly, the watermarked parameters may be recovered and checked against the parameters which were recorded (e.g., electronically or manually) at the time the image was taken so as to verify the authentic of the image as well as the recorded parameters.